Hi Linus.
Could you maybe do an unboxing and review of the D-Link DIR-645 Smart Beam Router?
It has 6 directional Antennas, enabling it to penetrate Walls more efficiently. Link.
I own it and it is great. I get full reception through 2 Stone walls, diagonally! And still showing a Link speed of up to 150MB/s. Full HD playback is no problem.
Reception is best in the Horizontal plane of the router, but it is still possible to reach adjacent Floors as well.